Description

When work on the incomplete cruiser Krasnyi Kavkaz was restarted in 1927, it had been planned to fit her with eight 8" (20.3 cm) guns in four twin turrets. However, it was quickly determined to be impossible to mount this much armament on the small and lightly constructed hull of this ship. Instead, four guns of the smaller caliber of 180 mm (7.1") were installed. These were 8"/50 (20.3 cm) Pattern 1905 guns relined down to 18 cm/60 (7.1"). These guns were to have had a very high muzzle velocity of 3,281 fps (1,000 mps) but initial trials showed that this would have given them a liner life of less than 10 rounds. The guns were derated but even then their life was quite short.

Early trials with these weapons showed numerous faults and so a new design was commissioned with a lower muzzle velocity and a shorter barrel length. This design was designated as the 180 mm/57 (7.1") B-1-P Pattern 1932. The early prototypes were of built-up construction, but in 1932 the technology of making loose liners for guns with bores from 3" to 8" (7.62 cm - 20.3 cm) was purchased from the Italian firm of Ansaldo. With this technology in hand, later versions of the 180 mm (7.1) guns were manufactured with loose liners. There were two differing liners used, one with deep grooves and one with shallow grooves. These liners were not interchangeable and required different ammunition.

Three coast defense mounts using these guns were in service. The first one was MO-8-180 using 8"/50 (20.3 cm) guns relined to 180 mm/56 (7.1") with ballistics identical to those of the B-1-P gun. A total of 9 mounts were built in 1933-35 and all were installed in the Far East. The second coastal mount was another open mounting designated as MO-1-180 and designed in 1934. A total of 42 mounts were built by June 1941 and these were installed in 12 batteries located all around the Soviet coastline. Those batteries that survived the war remained in active service use until the 1960s-70s.

The third coastal mount was the MB-2-180 twin turret designed in 1931-32. A total of eight turrets in 4 batteries were installed in the North in the 1930s-40s, six turrets in 3 batteries were installed along the Baltic coast by 1941, six turrets in 3 batteries were installed along the Pacific coast in the 1930s-40s and two turrets in 1 battery were installed along the Black Sea coast after the war. Surviving turrets were in use into 1990s.

Construction of the B-1-P was of loose liner, A tube, jacket and breech ring. Used Vickers piston breech, which opened upwards.

^The triple turret guns were in a common cradle. Both the mounting and the breech were electrically powered. These mountings were considered cramped and difficult to work, resulting in a low rate of fire. The triple mounting used a powered rammer.